Today my sister and I were listening to a radio talk show, and they were discussing the question "What is the moon".
First I thought "What a silly question is that! Of course a moon is a... ehm... it's a... " and there it stopped and I was confused.
My siblings and I started to think about it, but we're still not quite sure.

Some of the answers that were given on the radio were:
planet (I don't think so)
satellite (isn't that an artificial thing?)
or moon (now that one made sense to me )

Can anybody help us with that one?

Our moon is both a planet and satellite that we call "moon."

Looks like (as fjohn said) it's considered a "planet, a world and a satellite" according to this source:

http://vax.vmi.edu/MARION/%2BMOON/f79620002000/0

I still have some trouble with the satellite though.
It is obviously not the the technological devices we shoot into the orbit. But what is a satellite (e.g. opposed to a planet) ?

satellite, n, Astronomy. A celestial body that orbits a planet; a moon

(per www.dictionary.com)

Some of our planets in the solar system have satellite planets orbiting around the larger planet. These are moons (satellites). The moons have been captured by the larger planet and orbit around this one planet only because the planet has a greater gravitational force that holds the moon in place, neither approaching closer nor breaking away into space.
The technological devices that we shoot into orbit become earth satellites... with the correct placement they neither escape earth's gravity nor fall back to earth. Theoretically, they will orbit forever, but practically, the orbit decays over the years and they fall back to earth.

Thanks for the explanations.

The word comes from Old French (finding it's roots in Latin,) "Satelles", meaning "Hangers-on." The word originally referred to those people who hung about princes and other royalty in an attempt to make themselves look more important. Also could mean an attendant, like a page or a lady-in-waiting, for said royalty.

Someone somewhere along the line thought the small planets orbiting other planets resembled these types of people, and the word was applied to that as well. Which is also why it applies to man-made objects too. Anything that orbits a planet is a satellite.

The word "planet" is from Latin and literally means "Wanderer." The use of this word stems from the time when no telescopes were used, and astronomers thought that all celestial bodies were the same. Some bodies appeared to remain fixed relative to each other, and others seemed to move around in the sky. These wandering bodies became known as planets. It wasn't until the advent of telescopes that we discovered these bodies were in fact very different from the other visible celestial bodies, namely stars.

Since that time, the word planet has come to mean a non-luminous celestial body (one which does not produce it's own light) which is bigger than a meteor and lacks the coma of a comet. By this definition, moons do fit the bill, however the word is generally used to define only those bodies which also orbit a star rather than another planet. Therein lies the difference between a moon and a "planet." One orbits a sun, the other orbits another non-luminous body.

Arguing semantics about great masses is probably counterproductive to a true understanding of the situation.

Moon is loosely used to denote satellite, and vice-versa. Check your physics, and semantics.

Who was arguing? Arguing semantics in this case probably doesn't help gain understanding. But being clear about how and why certain words fit in certain cases IS essential to understanding.

If you have a predetermined idea of what the word satellite means, and someone calls something a satellite which you didn't think fit the definition, then surely an explanation of the word and it's meaning, and even how it came to mean that, would be in order to help you better understand...

Your point is well taken, and I meant no offense.